157611221 has 4 divisors (see below), whose sum is σ = 157686912. Its totient is φ = 157535532.

The previous prime is 157611197. The next prime is 157611247. The reversal of 157611221 is 122116751.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 122116751 = 2857 ⋅42743.

It is a cyclic number.

It is not a de Polignac number, because 157611221 - 2¹⁸ = 157349077 is a prime.

It is a super-2 number, since 2×157611221² = 49682593970221682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (157611281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34631 + ... + 38916.

It is an arithmetic number, because the mean of its divisors is an integer number (39421728).

Almost surely, 2^157611221 is an apocalyptic number.

It is an amenable number.

157611221 is a deficient number, since it is larger than the sum of its proper divisors (75691).

157611221 is an equidigital number, since it uses as much as digits as its factorization.

157611221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75690.

The product of its digits is 840, while the sum is 26.

The square root of 157611221 is about 12554.3307667115. The cubic root of 157611221 is about 540.1682386173.

Adding to 157611221 its reverse (122116751), we get a palindrome (279727972).

It can be divided in two parts, 157611 and 221, that multiplied together give a triangular number (34832031 = T₈₃₄₆).

The spelling of 157611221 in words is "one hundred fifty-seven million, six hundred eleven thousand, two hundred twenty-one".